Non-contacting instrumentation can be used for interrogating permanently implanted seeds which are sensitive to radiation. An electronic component dosimetry seed (EC/DS) would transpond a signal that reflects its total lifetime exposure to ionizing radiation. A seed that has two signals, one a reference signal which is not sensitive to radiation, would provide an intrinsic identification so that a reading proportional to accumulated radiation would be possible without obtaining the patient's original records. The seeds will be constructed and evaluated for sensitivity to radiation, accuracy, and stability. The desired specifications are to measure accumulated doses of up to 100 Gy to a sensitivity of l Gy. Such seeds would be useful in documenting delivered doses to patients in critical anatomical regions and in maintaining long term records in cases of a recurrent cancer. If three seeds could establish a field edge precisely, with permanence. This could be critical in cases for which sensitive tissues need to be protected such as near the edges of abutting fields and for doses delivered near the spinal cord. PROPOSED COMMERCIAL APPLICATION: Over one half million patients are so treated each year. Implanted dosimeters would give an indication of the true internal field delivered, especially near critical boundaries and would provide a permanent record of delivered radiation therapy which remains with the patient rather than in obscure files.